The feasibility of using the earth's crust under the oceans as a communications channel for very low frequency waves was studied. The structure of the crust and its electrical properties were used to evaluate the conductivity-depth profiles found in the literature. Using the impedance, E sub x/H sub y, a new phase function was defined that not only made the phase changes at the boundaries of the waveguide explicit, but also allowed the use of a computer for calculation of the propagation and attenuation constants. The system noise was assumed to come from two main sources: atmospherics and thermal effects. Calculation showed that beneath the ocean the atmospheric noise could be neglected. The thermal noise within the waveguide was calculated to be -162 dBm. The attenuation for the TM sub 10 mode was calculated to be -1.35 dB/km, thus allowing a transmission range of only about 163 km for 1 kW of transmitted power. The conclusion was that the crust under the ocean was not feasible as a long-range communications channel at VLF for the TM sub 10 mode.